Meta optical device and electronic apparatus including the same

ABSTRACT

A meta-optical device includes a plurality of phase modulation areas configured to modulate a phase of an incident light, each of the plurality of phase modulation areas including a plurality of nanostructures having a shape and an arrangement that are determined according to a respective rule set for each of the plurality of phase modulation areas; and a compensation area located between a kth phase modulation area and a (k+1)th phase modulation area adjacent to each other, from among the plurality of phase modulation areas, and including a compensation structure for buffering an effective refractive index change occurring in a boundary area between the kth phase modulation area and the (k+1)th phase modulation area according to respective rules of the kth phase modulation area and the (k+1)th phase modulation area, wherein N is a number of the plurality of phase modulation areas, k and N are natural numbers, and k is equal to or greater than 1 and less than N.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2020-0120029, filed on Sep. 17, 2020, in the Korean IntellectualProperty Office, the disclosure of which is incorporated by referenceherein in its entirety.

BACKGROUND 1. Field

Apparatuses and methods consistent with example embodiments relate to ameta-optical device and an electronic device including the same.

2. Description of the Related Art

A flat diffraction device including a meta-structure may exhibit variousoptical effects that conventional refraction devices may not achieve.Thus, such a flat diffraction device may be used to implement a thinoptical system, and accordingly, interests in using a thin opticalsystem in many fields have increased.

The meta-structure includes a nanostructure in which a value less thanthe wavelength of incident light is applied to shape, period, etc. Thenanostructure is designed such that a phase profile set for eachposition for light of a desired wavelength band is satisfied in order toobtain the desired optical performance. When discontinuity appears inthe phase profile, light diffraction occurs in an unintended direction,thereby lowering light efficiency.

SUMMARY

One or more example embodiments provide meta-optical devices withimproved diffraction efficiency.

Further, one or more example embodiments Provided are electronic devicesusing a meta-optical device.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments of the disclosure.

According to an aspect of an embodiment, there is provided ameta-optical device including: a plurality of phase modulation areasarranged in a first direction and configured to modulate a phase of anincident light, each of the plurality of phase modulation areascomprising a plurality of nanostructures having a shape and anarrangement that are determined according to a respective rule set foreach of the plurality of phase modulation areas; and a compensation arealocated between a k^(th) phase modulation area and a (k+1)^(th) phasemodulation area adjacent to each other, from among the plurality ofphase modulation areas, and comprising a compensation structure forbuffering an effective refractive index change occurring in a boundaryarea between the k^(th) phase modulation area and the (k+1)^(th) phasemodulation area according to respective rules of the k^(th) phasemodulation area and the (k+1)^(th) phase modulation area, wherein N is anumber of the plurality of phase modulation areas, k and N are naturalnumbers, and k is equal to or greater than 1 and less than N.

The k^(th) phase modulation area and the (k+1)^(th) phase modulationarea may be configured to modulate the phase of the incident light tohave a same sign of a phase change slope according to a position in thefirst direction.

Among the plurality of nanostructures in the k^(th) phase modulationarea, a width of a nanostructure closest to the compensation area in thefirst direction is w_(a), among the plurality of nanostructures in the(k+1)^(th) phase modulation area, a width of a nanostructure closest tothe compensation area in the first direction is w_(b), and a width w_(c)of the compensation structure is between w_(a) and w_(b).

The compensation structure may include two or more compensationstructures having a same width in the first direction and arranged inthe first direction.

The compensation structure may include two or more compensationstructures arranged in the first direction, and widths of the two ormore compensation structures may gradually change with a pattern ofchange from w_(a) to w_(b) in the first direction.

The plurality of phase modulation areas may have a circular shape or anannular shape surrounding the circular shape, and the first directionmay be a radial direction that extends from a center of the circularshape toward a boundary of the meta-optical device.

When the plurality of phase modulation areas are m^(th) areas, and m isgreater than or equal to 2 and increases from 2 to N in an order fromthe center, all of the m^(th) areas have a phase modulation range of afirst phase to a second phase in the radial direction, and the firstphase and the second phase may be different from each other and may bebetween −2π and 2π.

A difference between the first phase and the second phase may be 2π orless.

Widths of the plurality of phase modulation areas in the radialdirection may decrease in a direction from the center to the boundary ofthe meta-optical device.

The compensation area may include a plurality of compensation areas, andwidths of the plurality of compensation areas that are arranged in theradial direction may have a same value or decrease in a direction fromthe center to the boundary of the meta-optical device.

The compensation area may include a plurality of compensation areas, andin a phase modulation area and a compensation area at a positionadjacent to each other, from among the plurality of phase modulationareas and the plurality of compensation areas, a ratio of a width of thecompensation area to a width of the phase modulation area may increasein a direction from the center to the boundary of the meta-opticaldevice.

The ratio may be 25% or less.

The compensation area may include a plurality of compensation areas, anda ratio of a number of the plurality of compensation areas to a numberof the plurality of phase modulation areas may be 50% or more.

When a radius of the meta-optical device is R, a distance of thecompensation area from the center may be greater than R/2.

When an incident angle of the incident light is θ, the compensation areamay be provided at a position where θ is greater than or equal to 30°.

Each of the plurality of nanostructures and the compensation structuremay have a pillar shape.

The meta-optical device may further include: a substrate configured tosupport the plurality of nanostructures and the compensation structure;and a surrounding material layer covering the plurality ofnanostructures and the compensation structure and having a refractiveindex different from refractive indices of the plurality ofnanostructures and the compensation structure.

The meta-optical device may further include a substrate and asurrounding material layer arranged on the substrate, and each of theplurality of nanostructures and the compensation structure may have ahole shape such that the surrounding material layer is engraved.

The plurality of nanostructures and the compensation structure may bearranged in a multilayer structure stacked in a second directionperpendicular to the first direction.

The plurality of nanostructures may include a plurality of firstnanostructures arranged on a first layer and a plurality of secondnanostructures arranged on a second layer, and the compensationstructure may include a first compensation structure arranged on thefirst layer and a second compensation structure arranged on the secondlayer.

When viewed from the second direction, the first compensation structureand the second compensation structure may be arranged to be offset withrespect to each other in the first direction.

A length in the first direction in which the first compensationstructure and the second compensation structure are offset from eachother may increases as a position of the compensation area becomesfarther away from the center.

The meta-optical device may further include: a substrate configured tosupport the plurality of first nanostructures and the first compensationstructure; and a first surrounding material layer filling an areabetween the plurality of first nanostructures and the first compensationstructure on the substrate and having a refractive index different fromrefractive indices of the plurality of first nanostructures and thefirst compensation structure.

The meta-optical device may further include: a second surroundingmaterial layer filling an area between the plurality of secondnanostructures and the second compensation structure on the firstsurrounding material layer and having a refractive index different fromrefractive indices of the plurality of second nanostructures and thesecond compensation structure.

The meta-optical device may further include a second surroundingmaterial layer arranged on the substrate, and each of the plurality ofsecond nanostructures and the second compensation structure may have ahole shape such than the second surrounding material layer is engraved.

When a center wavelength of the incident light is λ₀, heights of theplurality of nanostructures and the compensation structure may begreater than λ₀/2 and less than 4λ₀.

The meta-optical device may be a lens.

Widths of the plurality of phase modulation areas in the first directionmay have an equal value.

The meta-optical device may be a beam deflector.

The meta-optical device may be a beam shaper.

The incident light may have an infrared wavelength or a visible lightwavelength.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will be more apparent by describingcertain example embodiments, with reference to the accompanyingdrawings, in which:

FIG. 1 is a plan view of a schematic configuration of a meta-opticaldevice according to an embodiment;

FIG. 2 is a graph showing an example of a phase profile of ameta-optical device according to an embodiment;

FIG. 3 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to an embodiment;

FIG. 4 is a graph showing a phase profile of light immediately afterpassing through the partial area shown in FIG. 3 according to anembodiment;

FIG. 5 is a cross-sectional view of an arrangement of nanostructures ofa meta-optical device according to a comparative example;

FIG. 6 is a graph showing a phase profile of light immediately afterpassing through the position of the nanostructure shown in FIG. 5according to an embodiment;

FIG. 7 is a graph showing a phase profile of a meta-optical deviceaccording to a comparative example;

FIG. 8 is a view of a modeled refractive index distribution structure tocomputationally simulate the effect of phase discontinuity of ameta-optical device according to a comparative example;

FIGS. 9A to 9C are views of a phase profile of light incident on thestructure of FIG. 8 at an incident angle of 0, 30, and 45 degrees,respectively;

FIG. 10 is a view of a modeled refractive index distribution structureto computationally simulate a function of a compensation area providedin a meta-optical device according to an embodiment;

FIGS. 11A to 11C are views of a phase profile of light incident on thestructure of FIG. 10 at an incident angle of 0, 30, and 45 degrees,respectively;

FIG. 12 is a view of a modeled refractive index distribution structureto computationally simulate a function of a compensation area providedin a meta-optical device according to another embodiment;

FIGS. 13A to 13C are views of a phase profile of light incident on thestructure of FIG. 12 at an incident angle of 0, 30, and 45 degrees,respectively;

FIG. 14 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to another embodiment;

FIG. 15 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to another embodiment;

FIG. 16 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to another embodiment;

FIG. 17 is a plan view of a structure of a meta-optical device accordingto another embodiment;

FIG. 18 is a plan view of a structure of a meta-optical device accordingto another embodiment;

FIG. 19 is a plan view of a structure of a meta-optical device accordingto another embodiment;

FIG. 20 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to another embodiment;

FIGS. 21A and 21B are perspective views of an example of a nanostructureincluded in a meta-optical device according to embodiments.

FIG. 22 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to another embodiment;

FIG. 23 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to another embodiment;

FIG. 24 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to another embodiment;

FIG. 25 is a cross-sectional view illustrating a partial area of astructure of a meta-optical device according to another embodiment;

FIG. 26 is a block diagram of a schematic configuration of an electronicdevice according to an embodiment;

FIG. 27 is a block diagram of a schematic configuration of a cameramodule included in the electronic device of FIG. 26 according to anembodiment;

FIG. 28 is a block diagram of a schematic configuration of a 3D sensorprovided in the electronic device of FIG. 26 according to an embodiment;

FIG. 29 is a block diagram of a schematic configuration of an electronicdevice according to another embodiment; and

FIG. 30 is a block diagram of a schematic configuration of aneye-tracking sensor provided in the electronic device of FIG. 29according to an embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. Expressionssuch as “at least one of,” when preceding a list of elements, modify theentire list of elements and do not modify the individual elements of thelist. For example, the expression, “at least one of a, b, and c,” shouldbe understood as including only a, only b, only c, both a and b, both aand c, both b and c, all of a, b, and c, or any variations of theaforementioned examples.

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings. The embodiments described below are onlyexamples, and thus, it should be understood that the embodiments may bemodified in various forms. The same reference numerals refer to the sameelements throughout. In the drawings, the sizes of constituent elementsmay be exaggerated for clarity.

For example, when an element is referred to as being “on” or “above”another element, it may be directly on the other element, or interveningelements may also be present.

It will be understood that, although the terms “first,” “second,” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are used only todifferentiate an element from another element. These terms do not limitthe material or structure of the components.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. In addition, it will be understood that when a unit isreferred to as “comprising” another element, it does not preclude thepossibility that one or more other elements may exist or may be added.

In addition, the terms “-er”, “-or”, and “module” described in thespecification mean units for processing at least one function and/oroperation and can be implemented by hardware components or softwarecomponents and combinations thereof.

The use of the terms “a,” “an,” and “the” and similar referents is to beconstrued to cover both the singular and the plural.

Operations constituting a method may be performed in any suitable orderunless explicitly stated that they should be performed in the orderdescribed. Further, the use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate the inventive concept and does not pose a limitation on thescope of the present disclosure unless otherwise claimed.

FIG. 1 is a plan view of a schematic configuration of a meta-opticaldevice according to an embodiment.

A meta-optical device 100 modulates a phase of incident light in acertain wavelength band, and includes a plurality of nanostructures NS.The certain wavelength band may be a visible light band, an infraredband, or a band including both. A nanostructure NS may be disposed on asubstrate SU, and in FIG. 1 , only a few nanostructures NS areexemplified for convenience. The nanostructure NS has a shape dimensionof a sub-wavelength less than a center wavelength λ₀ of the certainwavelength band, and has a refractive index different from those of thesubstrate SU and other surrounding materials. A detailed example of thenanostructure NS will be described in FIGS. 21A and 21B. Themeta-optical device 100 may implement various phase profiles forincident light according to the arrangement of the nanostructures NS.

The meta-optical device 100 includes a plurality of phase modulationareas including a plurality of nanostructures NS whose shape andarrangement are determined according to respective rules. The pluralityof phase modulation areas may be arranged in a certain directiondefining a phase profile, and this direction may be a radial direction rextending from a center C of the meta-optical device 100 to an outerboundary of the meta-optical device 100 as shown in FIG. 1 . However,the present disclosure is not limited thereto.

The nanostructure NS may be disposed on the substrate SU, and in FIG. 1, only a few nanostructures NS are exemplified for convenience. Theplurality of phase modulation areas will be referred to as a first areaR₁, a second area R₂, an N^(th) area R_(N), etc. in an order from thecenter C of the meta-optical device 100 in the radial direction r. Asillustrated, the first area R₁ may be a circular area, and the secondarea R₂ to the N^(th) area R_(N) may be annular areas.

A compensation area RC may be provided between a k^(th) area R_(k) and a(k+1)^(th) area R_(k+1) (k is a natural number between 1 and N) adjacentto each other, from among the plurality of phase modulation areas. Thecompensation area RC is illustrated as one area, but is not limitedthereto, and may be further provided at a position between the other twophase modulation areas. When rules of the first area R₁ to the N^(th)area R_(N) are set in order for the meta-optical device 100 to implementa desired phase profile, the compensation area RC is an area thatbuffers a sudden change in phase or a sudden change in effectiverefractive index occurring in a boundary area between two areasaccording to the respective rules of the two areas. The compensationarea RC provides a compensation structure CS having a shape and anarrangement suitable for this function is provided. The compensationstructure CS has a shape dimension of a sub-wavelength and has arefractive index different from that of a surrounding material. Thedetailed shape and arrangement of the compensation structure CS will bedescribed in detail later in FIG. 3 .

Rules set in each area of the meta-optical device 100 are applied toparameters such as shape, size (width and height), spacing, andarrangement of the nanostructure NS, and are set according to a phaseprofile that the meta-optical device 100 wants to implement as a whole.

When light enters the meta-optical device 100 in a z direction (e.g., adirection perpendicular to a surface plane of the substrate SU on whichthe nanostructure NS is disposed) and passes through the meta-opticaldevice 100, the light encounters refractive index distribution accordingto an arrangement of the plurality of nanostructures NS having arefractive index greater than 1. A position of a wavefront connectingpoints of the same phase in an optical path is different before andafter undergoing a refractive index distribution according to thearrangement of the nanostructures NS, which is expressed as a phasedelay. The degree of phase delay is different according to each positionthat is a variable of the refractive index distribution, that is, aposition (x and y coordinates) on a plane perpendicular to a lighttraveling direction (z direction) at a position immediately after lightpasses through the nanostructures NS of the meta-optical device 100.When the arrangement of the nanostructures NS has polar symmetry or hasrotational symmetry at a certain angle with respect to a z-axis, a phaseprofile may be expressed as a function of the distance r from the centerC. This phase profile appears differently depending on the detailedshape and arrangement of the nanostructures NS constituting themeta-optical device 100. In other words, the detailed shape andarrangement of the nanostructures NS set for each position may bedetermined according to a desired phase profile.

In the following, expressions such as phase delay, phase modulation, andphase may be used interchangeably, and all of these expressions refer toa relative phase based on before undergoing the refractive indexdistribution formed by the nanostructures NS at a position immediatelyafter light passes through the nanostructures NS.

A specific example of the arrangement of the nanostructures NS in themeta-optical device 100 described below is related to a case where themeta-optical device 100 functions as a lens, but embodiments are notlimited thereto. In a case in which the metal-optical device 100functions as a lens, the meta-optical device 100 may be referred to as ameta lens.

The first area R₁ to the N^(th) area R_(N) are areas exhibiting a phasedelay of a certain range, and a phase modulation range of the secondarea R₂ to the N^(th) area R_(N) may be the same. The phase modulationrange may be 2π radians or less. A phase modulation range of the firstarea R₁ may be 2π radians or less. All of the first to N^(th) areas R₁to R_(N) may be referred to as 2π zones.

The function of each area, and the number N or widths W₁, . . . W_(K), .. . and W_(N) of the areas may be major variables of the performance ofthe meta-optical device 100.

In order for the meta-optical device 100 to function as a lens, ruleswithin each area are set so that the width of each area is not constant,and a direction of diffraction of incident light in each area isslightly different. The number of areas is related to the magnitude (anabsolute value) of refractive power, and the sign of the refractivepower may be determined according to the rules within each area. Forexample, positive refractive power may be implemented by an arrangementof rules in which the size of the nanostructures NS decreases in theradial direction in each area (an arrangement with decreasing phases),and negative refractive power may be implemented by an arrangement ofrules in which the size of the nanostructures NS increases in the radialdirection (an arrangement with increasing phases).

In order for the meta-optical device 100 to function as a beamdeflector, rules within each area may be set such that the widths W₁, .. . W_(k), . . . and W_(N) of each area (R₁, R₂, . . . , and R_(N)) areconstant and incident light is diffracted in a certain and constantdirection in each area.

In addition to a lens or a beam deflector, the meta-optical device 100may function as a beam shaper having an arbitrary positionaldistribution.

In order for the above-described functions to appear efficiently withina desired wavelength band, discontinuities according to positions in aphase profile for this should not appear as much as possible. This isbecause, in a case of phase discontinuity, a portion of light passingthrough the meta-optical device 100 is diffracted in a direction otherthan a desired diffraction direction, and thus diffraction efficiencymay be deteriorated.

However, because the phase modulation areas R₁, . . . R_(k), . . . andR_(N) provided in the meta-optical device 100 modulate a phase ofincident light in the same range and/or trend, discontinuity of a largephase difference basically exists at the boundary between adjacentareas. The meta-optical device 100 according to the embodiment has thecompensation area RC capable of mitigating phase discontinuity at atleast one of these positions.

FIG. 2 is a graph exemplarily showing a phase profile of a meta-opticaldevice according to an embodiment.

Referring to the graph, the second area R₂, the third area R₃, and theN^(th) area R_(N) have optical properties of changing a phase of anincident light from π to −π in a radial direction within each area.Therefore, discontinuity in which the phase changes steeply from −π to πis formed at the boundary of these areas. The compensation area RClocated between two adjacent areas, that is, the k^(th) area R_(k) andthe (k+1)^(th) area R_(k+1), is provided such that phase modulationoccurs gradually from −π to π. That is, adjacent areas with thecompensation area RC therebetween, that is, the k^(th) area R_(k), thecompensation area RC, and the (k+1)^(th) area R_(k+1) become areaswithout phase discontinuity.

FIG. 3 is a cross-sectional view illustrating a structure of ameta-optical device according to an embodiment in detail in a partialarea, and FIG. 4 is a graph showing a phase profile of light immediatelyafter passing through the partial area shown in FIG. 3 .

FIG. 3 shows an arrangement of the nanostructures NS in the k^(th) areaR_(k), the compensation area RC, and the (k+1)^(th) area R_(k+1) incross section A-A of FIG. 1 .

Referring to FIG. 3 , the width D_(c) of the compensation structure CShas a value between D_(a) and D_(b) (e.g., a value greater than D_(a)and less than D_(b)) when a width of the nanostructure NS closest to thecompensation area RC among the nanostructures NS of the k^(th) areaR_(k) in the radial direction r is D_(a), and when a width of thenanostructure closest to the compensation area RC among thenanostructures NS of the (k+1)^(th) area R_(k+1) in the radial directionr is D_(b).

By the compensation structure CS, a phase modulation value in thecompensation area RC is an intermediate phase between a phase −π at theend of the k^(th) area R_(k) and a phase π at the start of the(k+1)^(th) area R_(k+1). Accordingly, phase discontinuity between twoadjacent phase modulation areas, that is, the k^(th) area R_(k) and the(k+1)^(th) area R_(k+1), is alleviated. A phase modulation trend in thecompensation area RC is opposite to that of the k^(th) area R_(k) andthe (k+1)^(th) area R_(k+1) adjacent thereto. In the k^(th) area R_(k)and the (k+1)^(th) area R_(k+1), the phase gradually decreases in theradial direction, whereas in the compensation area RC, the phaseincreases in the radial direction. Therefore, for example, when thek^(th) area R_(k) and the (k+1)^(th) area R_(k+1) are modified in a formin which the phase gradually increases in the radial direction, in thecompensation area RC, the phase decreases in the radial direction.

The alleviation of the phase discontinuity by the compensation area RCmay be described in terms of an effective refractive index. Theeffective refractive index is a concept that assumes that a unit elementof the meta-optical device 100 may be viewed as a uniform medium. Awidth of the nanostructure NS at the end of the k^(th) area R_(k) is thesmallest among the nanostructures NS in the k^(th) area R_(k), and awidth of the nanostructure NS at the start of the (k+1)^(th) areaR_(k+1) is the largest among the nanostructures NS in the (k+1)^(th)area R_(k+1). Accordingly, when a significant and sudden change in theeffective refractive index appears in the boundary area between thek^(th) area R_(k) and the (k+1)^(th) area R_(k+1), the compensationstructure CS provided in the compensation area RC buffers such aneffective refractive index change.

An effective refractive index change tendency in the compensation areaRC is opposite to an effective refractive index change tendency in thek^(th) area R_(k) and the (k+1)^(th) area R_(k+1) adjacent thereto. Inthe k^(th) area R_(k) and the (k+1)^(th) area R_(k+1), the effectiverefractive index gradually decreases in the radial direction, whereas inthe compensation area RC, the effective refractive index increases inthe radial direction. Therefore, for example, when the k^(th) area R_(k)and the (k+1)^(th) area R_(k+1) are modified in a form in which theeffective refractive index gradually increases in the radial direction,in the compensation area RC, the effective refractive index decreases inthe radial direction r.

FIG. 5 is a cross-sectional view illustrating a structure of ameta-optical device according to a comparative example in detail in apartial area, and FIG. 6 is a graph showing a phase profile of lightimmediately after passing through the partial area shown in FIG. 5 .

The meta-optical device of the comparative example does not have acompensation area, that is, the meta-optical device of the comparativeexample is same as the meta-optical device of FIG. 1 except for thecompensation area RC.

The k^(th) area R_(k) includes the nanostructures NS with a widthgradually decreasing in the radial direction r, and the phase changesfrom π to −π in the radial direction. The (k+1)^(th) area includes thenanostructures NS with a width gradually decreasing in the radialdirection r, and the phase changes from π to −π in the radial directionagain. In other words, an area between a location where the k^(th) areaR_(k) ends and a location where the (k+1)^(th) area R_(k+1) starts is anarea in which an effective refractive index changes rapidly, and thephase also shows discontinuity that changes rapidly from −π to π.

FIG. 7 is a graph showing a phase profile of a meta-optical deviceaccording to a comparative example.

Referring to the graph, in all adjacent areas, such as the boundarybetween the first area R₁ and the second area R₂ provided in themeta-optical device, and the boundary between the second area R₂ and thethird area R₃, phase discontinuity in which a phase rapidly changesoccurs.

The phase discontinuity may lower diffraction efficiency intended by themeta-optical device, which is due to a shadowing effect due todiscontinuous areas.

FIG. 8 is a view of a modeled refractive index distribution structure tocomputationally simulate the effect of phase discontinuity of ameta-optical device according to a comparative example. FIGS. 9A to 9Care views of a phase profile of light incident on the structure of FIG.8 at an incident angle of 0, 30, and 45 degrees, respectively.

The refractive index distribution structure of FIG. 8 includes arefractive index distribution in which an effective refractive indexchanges steeply from 1.75 to 2 on a substrate having a refractive indexof 1.46.

A wavefront of light that has undergone the steep change in theeffective refractive index is not continuous, and exhibits a shadowingeffect as indicated by reference SE in FIGS. 9A-9C. This effect is morepronounced as an incident angle increases.

FIG. 10 is a view of a modeled refractive index distribution structureto computationally simulate a function of a compensation area providedin a meta-optical device according to an embodiment, and FIGS. 11A to11C are views of a phase profile of light incident on the structure ofFIG. 10 at an incident angle of 0, 30, and 45 degrees, respectively.

The refractive index distribution structure of FIG. 10 is a distributionin which an effective refractive index changes stepwise to 1.75, n_(c),and 2 on a substrate having a refractive index of 1.46. As compared withFIG. 8 , the refractive index distribution structure of FIG. 10corresponds to a case in which a portion of an area having a refractiveindex of 2 is changed to a compensation structure having a refractiveindex of 1.871.

Comparing FIGS. 11A, 11B, and 11C with FIGS. 9A, 9B, and 9C,respectively, it can be seen that a shadowing effect is reduced.

FIG. 12 is a view of a modeled refractive index distribution structureto computationally simulate a function of a compensation area providedin a meta-optical device according to an embodiment, and FIGS. 13A to13C are views of a phase profile of light incident on the structure ofFIG. 12 at an incident angle of 0, 30, and 45 degrees, respectively.

The refractive index distribution structure of FIG. 12 is a distributionin which an effective refractive index changes stepwise to 1.75, nc1,nc2, nc3, and 2 on a substrate having a refractive index of 1.46. Ascompared with FIG. 8 , the refractive index distribution structure ofFIG. 12 corresponds to a case in which a portion of an area having arefractive index of 2 is changed to three compensation structures withrefractive indices of 1.8125, 1.871, and 1.9375.

Comparing FIGS. 13A, 13B, and 13C with FIGS. 9A, 9B, and 9C,respectively, it can be seen that a shadowing effect is reduced. Inaddition, comparing FIGS. 13A, 13B, and 13C with FIGS. 11A, 11B, and11C, respectively, it can be seen that the shadowing effect issignificantly reduced when a subdivided compensation structure isintroduced.

FIG. 14 is a cross-sectional view illustrating a structure of ameta-optical device according to another embodiment in detail in apartial area.

A meta-optical device 101 includes a compensation area RC1 providedbetween the k^(th) area R_(k) and the (k+1)^(th) area R_(k+1), andwidths of the two compensation structures CS of the compensation areaRC1 may increase according to positions of the compensation structuresCS in the radial direction. For example, when the compensationstructures CS includes a first compensation structure and a secondcompensation structure, and the first compensation structure is disposedcloser to the center C of the meta-optical device 101 than the secondcompensation structure (i.e., the second compensation structure isdisposed farther from the center C than the first compensationstructure), a width of the second compensation structure is greater thana width of the first compensation structure. Both the widths of thefirst and the second compensation structures may be greater than a widthof a nanostructure NS closest to the RC1 in the k^(th) area R_(k), andless than a width of a nanostructure NS closed to the RC in the(k+1)^(th) area R_(k+1),

FIG. 15 is a cross-sectional view illustrating a structure of ameta-optical device according to another embodiment in detail in apartial area.

A meta-optical device 102 includes a compensation area RC2 providedbetween the k^(th) area R_(k) and the (k+1)^(th) area R_(k+1), and thecompensation area RC2 includes the plurality of compensation structuresCS having the same width in a radial direction r and arranged in theradial direction r.

FIG. 16 is a cross-sectional view illustrating a structure of ameta-optical device according to another embodiment in detail in apartial area.

A meta-optical device 103 includes a compensation area RC3 providedbetween the k^(th) area R_(k) and the (k+1)^(th) area R_(k+1), and thecompensation area RC3 includes the plurality of compensation structuresCS arranged in a form in which their width gradually increases in theradial direction (r). The number of compensation structures CS isrelated to a width of the compensation area RC3, and the width of thecompensation area RC3 may be determined considering widths of the k^(th)area R_(k) and the (k+1)^(th) area R_(k+1) adjacent to the compensationarea RC3.

FIG. 17 is a plan view of a structure of a meta-optical device accordingto another embodiment.

A meta-optical device 104 may include a plurality of compensation areasRC4. A compensation area RC4 may be provided between all adjacent phasemodulation areas R₁, . . . R_(k), and . . . R_(N), but is not limitedthereto, and may be provided in some of these areas. A ratio of thenumber of a plurality of compensation areas to the number of a pluralityof phase modulation areas may be approximately 50% or more.

In a phase modulation area PA and a compensation area RC4 at positionsadjacent to each other, from among a plurality of phase modulation areasand a plurality of compensation areas, a ratio (W_(c)/W_(p)) of a widthW_(c) of a compensation area RC4 to a width W_(p) of a phase modulationarea PA may increase as a position of the compensation area is furtheraway from the center C. As described above, it is considered that theeffect of the compensation area RC4 appears well when an incident angleof light is larger. For example, when the meta-optical device 104functions as a lens, the closer to the center, the closer an incidentangle of light is to 0 degrees, and the further away from the center,the larger the incident angle of light. Accordingly, the ratio of thewidth W_(p) of the phase modulation area PA and the width W_(c) of thecompensation area RC4 that are located adjacent to each other may be setsuch that the action of the compensation area RC4 is strengthened towardthe periphery. In other words, this ratio may be expressed as a ratio ofthe number of compensation structures arranged in the compensation areaRC4 in the radial direction to the number of nanostructures arranged inthe phase modulation area PA in the radial direction.

The ratio (W_(c)/W_(p)) gradually increases from the center to theperiphery, and may reach about 20% to about 25% at the most periphery.This ratio (W_(c)/W_(p)) may increase as an effective aperture ratio(R/f) of the meta-optical device 104 increases, wherein f and R denote afocal length and an effective radius of the meta-optical device 104,respectively. For example, when the effective aperture ratio of themeta-optical device 104 is 0.8, the value of the ratio may be about 25%.

The widths of the compensation area RC4 may be all the same as shown,but are not limited thereto. Any one of the above-described compensationareas RC, RC1, RC2, and RC3 may be applied to the compensation area RC4.

FIG. 18 is a plan view of a structure of a meta-optical device accordingto another embodiment.

A plurality of compensation areas RC5 may be included in a meta-opticaldevice 105, or may be provided between all the adjacent phase modulationareas R₁, . . . R_(k), and . . . R_(N), and the width thereof decreasesas the distance from the center C increases. As shown, in a case wherethe width of the first area R1 to the N^(th) area R_(N) graduallydecreases in a direction away from the center C, the width of thecompensation areas RC5 may also decrease as the distance from the centerC increases. Even in this case, in the phase modulation area PA and thecompensation area RC5 at positions adjacent to each other, from amongthe plurality of phase modulation areas R_(k) and the plurality ofcompensation areas RC4, the ratio (W_(c)/W_(p)) of the width W_(c) ofthe compensation area RC5 to the width W_(p) of the phase modulationarea PA may increase as the position of the compensation area RC5 isfurther away from the center C. However, the present disclosure is notlimited thereto, and the ratio (W_(c)/W_(p)) may be constant.

FIG. 19 is a plan view of a structure of a meta-optical device accordingto another embodiment.

A compensation area RC6 provided in a meta-optical device 106 may bearranged at a peripheral portion among positions between the adjacentphase modulation areas R₁, . . . R_(k), and . . . R_(N). It isconsidered that an effect of the compensation area RC6 appears well inan area where an incident angle of light is larger. When themeta-optical device 106 functions as a lens, the closer to the center,the closer an incident angle of light is to 0 degrees, and the furtheraway from the center, the larger the incident angle of light. In orderto efficiently represent a function of the compensation area RC6, thecompensation area RC6 may be provided on a peripheral side, for example,at a position where the incident angle of light is 30 degrees or more.For example, when an effective radius of the meta-optical device 106 isR, the compensation area RC6 may be provided at a position where thedistance from the center is R/2 or more. In this embodiment, the numberof compensation areas RC6 is minimized, and diffraction efficiencyreduction due to phase discontinuity may be effectively prevented.

FIG. 20 is a cross-sectional view illustrating a structure of ameta-optical device according to another embodiment in detail in apartial area.

A meta-optical device 107 includes a substrate SU, the nanostructure NSand the compensation structure CS arranged on the substrate SU, and asurrounding material layer 150 covering the nanostructure NS and thecompensation structure CS.

The substrate SU has a property of being transparent to light in anoperating wavelength band of the meta-optical device 107, and mayinclude any one of glass (fused silica, BK7, etc.), quartz, polymer(PMMA, SU-8, etc.), and other transparent plastics.

The nanostructure NS and the compensation structure CS include amaterial having a refractive index difference from a surroundingmaterial such as the surrounding material layer 150 and the substrateSU. For example, the material may have a high refractive index with adifference of 0.5 or more from refractive indices of surroundingmaterials, or a low refractive index with a difference of 0.5 or morefrom refractive indices of surrounding materials. The nanostructure NSand the compensation structure CS may include a material having the samerefractive index.

When the nanostructure NS and the compensation structure CS include amaterial having a higher refractive index than those of surroundingmaterials, the nanostructure NS and the compensation structure CS mayinclude at least one of c-Si, p-Si, and a-Si III-V compoundsemiconductor (GaAs, GaP, GaN, GaAs, etc.), SiC, TiO2, TiSiOx, and SiN,and a low refractive index surrounding material may include a polymermaterial such as SU-8 and PMMA, SiO₂, or SOG.

When the nanostructure NS and the compensation structure CS include amaterial having a lower refractive index than those of surroundingmaterials, the nanostructure NS and the compensation structure CS mayinclude SiO₂ or air, and a high refractive index surrounding materialmay include at least one of c-Si, p-Si, and a-Si III-V compoundsemiconductor (GaAs, GaP, GaN, GaAs, etc.), SiC, TiO₂, TiSiO_(x), andSiN.

FIGS. 21A and 21B are perspective views of an exemplary form of ananostructure included in a meta-optical device according toembodiments.

The nanostructure NS and the compensation structure CS may be a columnarstructure. For example, the nanostructure NS and the compensationstructure CS may have a cylindrical shape as shown in FIG. 21A or asquare column shape as shown in FIG. 21B. A width D of the nanostructureNS and the compensation structure CS is a sub-wavelength, and a height Hmay be greater than the center wavelength λ₀ of an operating wavelengthband. For example, the height H may be greater than λ₀/2 and less than4λ₀. In addition to the illustrated shapes, various pillar shapes havinga cross-sectional shape of a rectangle, a cross shape, a polygon, or anellipse may be applied to the nanostructure NS and the compensationstructure CS.

Heights of the plurality of nanostructures and the compensationstructure may be greater than a center wavelength of the certainwavelength band.

FIG. 22 is a cross-sectional view illustrating a structure of ameta-optical device according to another embodiment in detail in apartial area.

A meta-optical device 108 includes the substrate SU, and the pluralityof nanostructures NS and the compensation structure CS formed on thesubstrate SU.

The nanostructure NS and the compensation structure CS are differentfrom the above-described embodiments in that the surrounding materiallayer 160 is engraved with a hole of a certain pillar shape, forexample, a cylindrical shape as shown in FIG. 21A or a square pillarshape as shown in FIG. 21B.

The width D_(c) of the hole forming the compensation structure CS has avalue between a width D_(a) of a hole forming the nanostructure NSclosest to a compensation area RC8 among the nanostructures NS of thek^(th) area R_(k) and a width D_(b) of a hole forming the nanostructureNS closest to the compensation area RC8 among the nanostructures NS ofthe (k+1)^(th) area R_(k+1).

FIG. 23 is a cross-sectional view illustrating a structure of ameta-optical device according to another embodiment in detail in apartial area.

A meta-optical device 109 includes the substrate SU, and a plurality ofnanostructures NS1 and NS2 and compensation structures CS1 and CS2formed on the substrate SU. The meta-optical device 109 of thisembodiment is different from the above-described embodiments in that thenanostructures NS1 and NS2 and the compensation structures CS1 and CS2are arranged in a two-layer structure.

The plurality of nanostructures NS1 and the compensation structure CS1are arranged on the substrate SU, and a first surrounding material layer151 covering the plurality of nanostructures NS1 and the compensationstructure CS1 is formed. The plurality of nanostructures NS2 and thecompensation structure CS2 are formed on the first surrounding materiallayer 151. A thickness of the first surrounding material layer 151 isshown to match heights of a nanostructure NS1 and the compensationstructure CS1, but this is exemplary and is not limited thereto. Thethickness of the first surrounding material layer 151 may be greaterthan the heights of the nanostructure NS1 and the compensation structureCS1. A nanostructure NS2 and the compensation structure CS2 may beformed in a form such that a second surrounding material layer 161 isengraved into a certain pillar shape. A width of the compensationstructure CS1 located in a first layer of a compensation area RC9 has avalue between widths of two adjacent nanostructures NS1. Thecompensation structure CS2 located in a second layer of the compensationarea RC9 has an intaglio shape, and a width of the hole has a valuebetween widths of holes forming two adjacent nanostructures NS2.

Hereinafter, the description of a multilayer structure will be describedas the second layer forming the nanostructure NS2 and the compensationstructure CS2 in a form such that a surrounding material layer 161 isengraved, but is not limited thereto. The second layer may also have thenanostructure NS1 and the compensation structure CS1 similar to those ofthe first layer.

FIG. 24 is a cross-sectional view illustrating a structure of ameta-optical device according to another embodiment in detail in apartial area.

A meta-optical device 110 is similar to the embodiment of FIG. 23 inthat the nanostructure NS and the compensation structure CS are arrangedin a multilayer structure, and is different from the embodiment of FIG.23 in that a compensation area RC10 is shifted toward the radialdirection r when viewed in the z direction. The compensation area RC10is formed in this way so that the compensation area RC10 functions wellnot only for incident light L1 incident at an incident angle of 0degrees, but also for incident light L2 incident at a certain incidentangle.

FIG. 25 is a cross-sectional view illustrating a structure of ameta-optical device according to another embodiment in detail in apartial area.

A meta-optical device 111 is similar to the embodiment of FIG. 24 inthat the nanostructure NS and the compensation structure CS are arrangedin a multilayer structure and a compensation area RC11 is shifted towardthe radial direction r when viewed in a stacking direction (the zdirection). The degree to which the compensation area RC11 is shiftedtoward the radial direction r is illustrated to be a little greater thanthe embodiment of FIG. 23 . The compensation area RC11 may function wellfor the incident light L1 incident at an incident angle of 0 degrees andincident light L3 incident at a larger incident angle.

The embodiment of FIG. 23 , the embodiment of FIG. 24 , and theembodiment of FIG. 25 may be applied to a meta-optical device of anotherembodiment. In a position where an incident angle of light is small, thecompensation area RC9 may be formed in the shape illustrated in FIG. 23, in a position where the incident angle of light is a little larger,the compensation area RC10 may be formed in the shape illustrated inFIG. 24 , and in a position where the incident angle of light is thelargest, the compensation area RC11 may be formed in the shapeillustrated in FIG. 25 .

The above-described meta-optical devices may be applied to variouselectronic devices. For example, the above-described meta-opticaldevices may be mounted on electronic devices such as smartphones,wearable devices, Internet of Things (IoT) devices, home appliances,tablet personal computers (PCs), personal digital assistants (PDA),portable multimedia players (PMP), navigation, drones, robots,driverless vehicles, autonomous vehicles, and advanced driver assistancesystems (ADAS).

FIG. 26 is a block diagram of a schematic configuration of an electronicdevice according to an embodiment.

Referring to FIG. 26 , in a network environment 2200, an electronicdevice 2201 may communicate with another electronic device 2202 througha first network 2298 (near-field wireless communication network, etc.),or may communicate with another electronic device 2204 and/or a server2208 through a second network 2299 (telecommunications network, etc.).The electronic device 2201 may communicate with the electronic device2204 through the server 2208. The electronic device 2201 may include aprocessor 2220, a memory 2230, an input device 2250, an audio outputdevice 2255, a display device 2260, an audio module 2270, a sensormodule 2210, an interface 2277, a haptic module 2279, a camera module2280, a power management module 2288, a battery 2289, a communicationmodule 2290, a subscriber identification module 2296, and/or an antennamodule 2297. In the electronic device 2201, some (the display device2260, etc.) of these components may be omitted, or other components maybe added. Some of these components may be implemented in one integratedcircuit. For example, a fingerprint sensor 2211 of the sensor module2210, or an iris sensor, an illuminance sensor, etc. may be implementedby being embedded in the display device 2260 (a display, etc.).

The processor 2220 may execute software (a program 2240, etc.) tocontrol one or more other components (hardware or software components,etc.) of the electronic device 2201 connected to the processor 2220, andmay perform a variety of data processing or operations. As a portion ofthe data processing or operations, the processor 2220 may loadinstructions and/or data received from other components (the sensormodule 2210, the communication module 2290, etc.) into a volatile memory2232, may process instructions and/or data stored in the volatile memory2232, and may store result data in a nonvolatile memory 2234. Theprocessor 2220 may include a main processor 2221 (a central processingunit, an application processor, etc.) and an auxiliary processor 2223 (agraphics processing unit, an image signal processor, a sensor hubprocessor, a communication processor, etc.) that may be operatedindependently or together. The auxiliary processor 2223 uses less powerthan the main processor 2221 and may perform specialized functions.

The auxiliary processor 2223 may control functions and/or states relatedto some (the display device 2260, the sensor module 2210, thecommunication module 2290, etc.) of the components of the electronicdevice 2201 on behalf of the main processor 2221 while the mainprocessor 2221 is in an active (e.g., sleep) state or with the mainprocessor 2221 while the main processor 2221 is in an inactive (e.g.,application execution) state. The auxiliary processor 2223 (an imagesignal processor, a communication processor, etc.) may be implemented asa portion of other functionally relevant components (the camera module2280, the communication module 2290, etc.).

The memory 2230 may store a variety of data required by components (theprocessor 2220, the sensor module 2276, etc.) of the electronic device2201. The data may include, for example, software (the program 2240,etc.) and input data and/or output data for commands related thereto.The memory 2230 may include the volatile memory 2232 and/or thenonvolatile memory 2234.

The program 2240 may be stored as software in the memory 2230, and mayinclude an operating system 2242, middleware 2244, and/or an application2246.

The input device 2250 may receive commands and/or data to be used forthe components (the processor 2220, etc.) of the electronic device 2201from the outside (a user, etc.) of the electronic device 2201. The inputdevice 2250 may include a microphone, mouse, keyboard, and/or digitalpen (a stylus pen, etc.).

The audio output device 2255 may output an audio signal to the outsideof the electronic device 2201. The audio output device 2255 may includea speaker and/or a receiver. The speaker may be used for generalpurposes such as multimedia playback or recording playback, and thereceiver may be used to receive incoming calls. The receiver may becombined as a portion of the speaker or may be implemented as a separatedevice.

The display device 2260 may visually provide information to the outsideof the electronic device 2201. The display device 2260 may include adisplay, a hologram device, or a projector, and a control circuit forcontrolling the devices. The display device 2260 may include a touchcircuitry set to sense a touch, and/or a sensor circuit (a pressuresensor, etc.) configured to measure the intensity of force generated bythe touch.

The audio module 2270 may convert sound into an electrical signal, orvice versa. The audio module 2270 may obtain sound through the inputdevice 2250, or may output sound through the audio output device 2255and/or speakers and/or headphones of another electronic device (anelectronic device 2102, etc.) directly or wirelessly connected to theelectronic device 2201.

The sensor module 2210 may detect an operating state (power,temperature, etc.) of the electronic device 2201 or an externalenvironmental state (user status, etc.), and may generate an electricalsignal and/or a data value corresponding to the detected state. Thesensor module 2210 may include the fingerprint sensor 2211, anacceleration sensor 2212, a position sensor 2213, a 3D sensor 2214,etc., and may further include an iris sensor, a gyro sensor, an airpressure sensor, a magnetic sensor, a grip sensor, a proximity sensor, acolor sensor, an infrared (IR) sensor, a biometric sensor, a temperaturesensor, a humidity sensor, and/or an illuminance sensor.

The 3D sensor 2214 senses shape and movement of an object by radiatingcertain light onto the object and analyzing light reflected by theobject, and may include any one of the meta-optical devices 100, 101,102, 103, 104, 105, and 106 according to the above-describedembodiments.

The interface 2277 may support one or more designated protocols, whichmay be used to directly or wirelessly connect the electronic device 2201with other electronic devices (the electronic device 2102, etc.). Theinterface 2277 may include a high definition multimedia interface(HDMI), a universal serial bus (USB) interface, a secure digital (SD)card interface, and/or an audio interface.

A connection terminal 2278 may include a connector through which theelectronic device 2201 may be physically connected to other electronicdevices (the electronic device 2102, etc.). The connection terminal 2278may include an HDMI connector, a USB connector, an SD card connector,and/or an audio connector (a headphone connector, etc.).

The haptic module 2279 may convert electrical signals into a mechanicalstimulus (vibration, movement, etc.) or an electrical stimulus that theuser may perceive through tactile or motor sensations. The haptic module2279 may include a motor, a piezoelectric element, and/or an electricalstimulation device.

The camera module 2280 may capture a still image and a moving image. Thecamera module 2280 may include a lens assembly including one or morelenses, image sensors, image signal processors, and/or flashes. The lensassembly included in the camera module 2280 may collect light emittedfrom an object to be image captured, and may include any one of themeta-optical devices 100-111 according to the above-describedembodiments.

The power management module 2288 may manage power supplied to theelectronic device 2201. The power management module 388 may beimplemented as a portion of a power management integrated circuit PMIC.

The battery 2289 may supply power to components of the electronic device2201. The battery 2289 may include a non-rechargeable primary battery, arechargeable secondary battery, and/or a fuel cell.

The communication module 2290 may support establishment of a direct(wired) communication channel and/or a wireless communication channelbetween the electronic device 2201 and other electronic devices (theelectronic device 2102, an electronic device 2104, a server 2108, etc.),and communication through the established communication channel. Thecommunication module 2290 operates independently of the processor 2220(an application processor, etc.) and may include one or morecommunication processors supporting direct communication and/or wirelesscommunication. The communication module 2290 may include a wirelesscommunication module 2292 (a cellular communication module, ashort-range wireless communication module, a global navigation satellitesystem (GNSS), etc.) and/or a wired communication module 2294 (a localarea network (LAN) communication module, a power line communicationmodule, etc.). The corresponding communication module among thesecommunication modules may communicate with other electronic devicesthrough the first network 2298 (a local area network such as Bluetooth,WiFi Direct, or Infrared Data Association (IrDA)) or the second network2299 (a telecommunication network such as a cellular network, theInternet, or computer networks (LAN, WAN, etc.)). These various types ofcommunication modules may be integrated into a single component (asingle chip, etc.) or may be implemented as a plurality of separatecomponents (multiple chips). The wireless communication module 2292 mayidentify and authenticate the electronic device 2201 within acommunication network such as the first network 2298 and/or the secondnetwork 2299 using subscriber information (an international mobilesubscriber identifier (IMSI), etc.) stored in the subscriber identitymodule 2296.

The antenna module 2297 may transmit and/or receive signals and/or powerto and/or from the outside (other electronic devices, etc.). An antennamay include a radiator made of a conductive pattern formed on asubstrate (PCB, etc.). The antenna module 2297 may include one or moreantennas. When a plurality of antenna are included, the communicationmodule 2290 may select an antenna suitable for a communication methodused in a communication network, such as the first network 2298 and/orthe second network 2299, among the plurality of antennas. Signals and/orpower may be transmitted or received between the communication module2290 and other electronic devices through the selected antenna. Othercomponents (RFIC, etc.) besides the antenna may be included as a portionof the antenna module 2297.

Some of the components may be connected to each other and exchangesignals (command, data, etc.) through a communication method betweenperipheral devices (a bus, general purpose input and output (GPIO), aserial peripheral interface (SPI), a mobile industry processor interface(MIPI), etc.).

Commands or data may be transmitted or received between the electronicdevice 2201 and the external electronic device 104 through the server2108 connected to the second network 2299. The other electronic devices2202 and 2204 may be the same as or different from the electronic device2201. All or some of the operations executed in the electronic device2201 may be executed in one or more of the other electronic devices2202, 2204, and 2208. For example, when the electronic device 2201 needsto perform certain functions or services, the electronic device 2201 mayrequest one or more other electronic devices to perform some or all ofthe functions or services instead of directly executing the functions orservices. One or more other electronic devices that have received therequest may execute an additional function or service related to therequest, and may transfer a result of the execution to the electronicdevice 2201. To this end, cloud computing, distributed computing, and/orclient-server computing technologies may be used.

FIG. 27 is a block diagram of a schematic configuration of a cameramodule included in the electronic device of FIG. 26 .

Referring to FIG. 27 , the camera module 2280 may include a lensassembly 2310, a flash 2320, an image sensor 2330, an image stabilizer2340, a memory 2350 (a buffer memory, etc.), and/or an image signalprocessor 2360. The lens assembly 2310 may collect light emitted from anobject to be image captured, and may include any one of the meta-opticaldevices 100-111. The lens assembly 2310 may include one or morerefractive lenses and a meta-optical device. The meta-optical deviceprovided therein may be designed as a lens having a certain phaseprofile and having a compensation structure to reduce phasediscontinuity. The lens assembly 2310 including such a meta-opticaldevice implements desired optical performance and may have a shortoptical length.

In addition, the camera module 2280 may further include an actuator. Theactuator may drive a position of lens elements constituting the lensassembly 2310 for zooming and/or autofocus (AF), and may adjust aseparation distance between the lens elements.

The camera module 2280 may include a plurality of lens assemblies 2310,and in this case, may be a dual camera, a 360-degree camera, or aspherical camera. Some of the plurality of lens assemblies 2310 may havethe same lens properties (angle of view, focal length, autofocus, FNumber, optical zoom, etc.) or different lens properties. The lensassembly 2310 may include a wide-angle lens or a telephoto lens.

The flash 2320 may emit light used to enhance light emitted or reflectedfrom an object. The flash 2320 may include one or more light emittingdiodes (red-green-blue (RGB) LED, white LED, infrared LED, ultravioletLED, etc.), and/or a xenon lamp. The image sensor 2330 may be the imagesensor 1200 described with reference to FIGS. 1, 5 and 7 , and mayobtain an image corresponding to the object by converting light emittedor reflected from the object and transferred through the lens assembly2310 into an electrical signal. The image sensor 2330 may include one ora plurality of sensors selected from image sensors having differentattributes, such as an RGB sensor, a black and white (BW) sensor, an IRsensor, or a UV sensor. Each of the sensors included in the image sensor2330 may be implemented as a charged coupled device (CCD) sensor and/ora complementary metal oxide semiconductor (CMOS) sensor.

The image stabilizer 2340 may move one or a plurality of lenses or theimage sensor 2330 included in the lens assembly 2310 in a specificdirection in response to movement of the camera module 2280 or anelectronic device 2301 including the same, or may control an operatingcharacteristic of the image sensor 2330 (adjustment of read-out timing,etc.) such that a negative effect due to movement is compensated. Theimage stabilizer 2340 may detect movement of the camera module 2280 orthe electronic device 2301 using a gyro sensor or an acceleration sensorarranged inside or outside the camera module 2280. The image stabilizer2340 may be implemented optically.

In the memory 2350, some or all of the data obtained through the imagesensor 2330 may be stored for the next image processing operation. Forexample, when a plurality of images are obtained at high speed, theobtained original data (Bayer-patterned data, high-resolution data,etc.) may be stored in the memory 2350 and only a low-resolution imageis displayed, and then the memory 2350 may be used to transfer theoriginal data of a selected image (user selection, etc.) may betransferred to the image signal processor 2360. The memory 2350 may beintegrated into the memory 2230 of the electronic device 2201 or may beconfigured as a separate memory that is independently operated.

The image signal processor 2360 may perform one or more image processeson an image obtained through the image sensor 2330 or image data storedin the memory 2350. The one or more image processes may include depthmap generation, three-dimensional modeling, panorama generation, featurepoint extraction, image synthesis, and/or image compensation (noisereduction, resolution adjustment, brightness adjustment, blurring,sharpening, softening, etc.). The image signal processor 2360 maycontrol (exposure time control, or read-out timing control, etc.)components (the image sensor 2330, etc.) included in the camera module2280. An image processed by the image signal processor 2360 may bestored again in the memory 2350 for further processing or may beprovided to external components (the memory 2230, the display device2260, the electronic device 2202, the electronic device 2204, the server2208, etc.) of the camera module 2280. The image signal processor 2360may be integrated into the processor 2220 or may be configured as aseparate processor that operates independently of the processor 2220.When the image signal processor 2360 is configured as a separateprocessor from the processor 2220, an image processed by the imagesignal processor 2360 may be displayed through the display device 2260after further image processing by the processor 2220.

The electronic device 2201 may include a plurality of camera modules2280 having respective attributes or functions. In this case, one of theplurality of camera modules 2280 may be a wide-angle camera, and theother may be a telephoto camera. Similarly, one of the plurality ofcamera modules 2280 may be a front camera, and the other may be a rearcamera.

FIG. 28 is a block diagram of a schematic configuration of athree-dimensional (3D) sensor provided in the electronic device of FIG.26 .

The 3D sensor 2214 radiates certain light onto an object and receivesand analyzes light reflected by the object to sense shape and movementof the object. The 3D sensor 2214 includes a light source 2420, ameta-optical device 2410, a photodetector 2430, a signal processor 2440,and a memory 2450. As the meta-optical device 2410, any one of themeta-optical devices 100-111 according to the above-describedembodiments may be employed, and a target phase delay profile may be setto function as a beam deflector or a beam shaper.

The light source 2420 radiates light to be used for analyzing the shapeor position of an object. The light source 2420 may include a lightsource that generates and radiates light having a small wavelength. Thelight source 2420 may include a light source such as a laser diode (LD),a light emitting diode (LED), a super luminescent diode (SLD) thatgenerates and radiates light in a wavelength band suitable for analysisof the position and shape of an object, for example, light in aninfrared band wavelength. The light source 2420 may be a laser diode ofa variable wavelength. The light source 2420 may generate and irradiatelight of a plurality of different wavelength bands. The light source2420 may generate and radiate pulsed light or continuous light.

The meta-optical device 2410 modulates light radiated from a lightsource 1100 and transmits the modulated light to an object. When themeta-optical device 2410 is a beam deflector, the meta-optical device2410 may deflect incident light in a certain direction to direct theincident light toward an object. When the meta-optical device 2410 is abeam shaper, the meta-optical device 2410 modulates incident light suchthat the incident light has distribution having a certain pattern. Themeta-optical device 2410 may form structured light suitable for 3D shapeanalysis.

The photodetector 2430 receives reflected light of light radiated ontothe object through the meta-optical device 2410. The photodetector 2430may include an array of a plurality of sensors for sensing light, or mayinclude only one sensor.

The signal processor 2440 may analyze a shape of the object byprocessing a signal sensed by the photodetector 2430. The signalprocessor 2440 may analyze a 3D shape including a depth position of theobject. The signal processor 2440 may be integrated into the processor2220 shown in FIG. 26 .

For the 3D shape analysis, an operation for measuring an optical flighttime may be performed. Various calculation methods may be used tomeasure the optical flight time. For example, in a direct timemeasurement method, a distance is obtained by projecting pulsed lightonto an object and measuring the time when the light is reflected andreturned to the object with a timer. In a correlation method, pulsedlight is projected onto an object and a distance is measured frombrightness of the light reflected by the object and returned. In a phasedelay measurement method, a continuous wave light such as a sine wave isprojected onto an object, and a phase difference of the light reflectedand returned is detected and converted into a distance.

When an object is irradiated with structured light, a depth position ofthe object may be calculated from a pattern change of the structuredlight reflected by the object, that is, a result of comparison with anincident structured light pattern. Depth information of the object maybe extracted by tracking a pattern change for each coordinate of thestructured light reflected by the object, and 3D information related toshape and movement of the object may be extracted from the depthinformation of the object.

The memory 2450 may store programs and other data necessary for theoperation of the signal processor 2440.

An operation result of the signal processor 2440, that is, informationabout shape and position of the object may be transmitted to anotherunit in the electronic device 2301 or to another electronic device. Forexample, this information may be used in the application 2246 stored inthe memory 2230. Another electronic device to which a result istransmitted may be a display device or a printer that outputs theresult. In addition, the electronic device may be self-driving devicessuch as driverless cars, autonomous vehicles, robots, drones, etc.,smart phones, smart watches, mobile phones, PDAs, laptop computers, PCs,various wearable devices, other mobile or non-mobile computing devices,and IoT devices, but is not limited thereto.

FIG. 29 is a block diagram of a schematic configuration of an electronicdevice according to another embodiment.

An electronic device 3000 of FIG. 29 may be a glasses-type augmentedreality device. The electronic device 3000 includes a display engine3400, a processor 3300, an eye-tracking sensor 3100, an interface 3500,and a memory 3200.

The processor 3300 may control the overall operation of an augmentedreality device including the display engine 3400 by driving an operatingsystem or an application program, and may process and calculate avariety of data including image data. For example, the processor 3300may process image data including a left-eye virtual image and aright-eye virtual image rendered to have binocular parallax.

The interface 3500 is input/output of data or manipulation commands fromthe outside, and may include, for example, a user interface such as atouch pad, a controller, and manipulation buttons that a user canmanipulate. The interface 3500 may include a wired communication modulesuch as a USB module or a wireless communication module such asBluetooth, and may receive operation information of a user or data of avirtual image transmitted from an interface included in an externaldevice through them.

The memory 3200 may include an internal memory such as volatile memoryor nonvolatile memory. The memory 3200 may store a variety of data,programs, or applications for driving and controlling an augmentedreality device under the control of the processor 3300 and data ofinput/output signals or virtual images.

The display engine 3400 is configured to generate light of a virtualimage by receiving image data generated by the processor 3300, andincludes a left-eye optical engine 3410 and a right-eye optical engine3420. Each of the left-eye optical engine 3410 and the right-eye opticalengine 3420 includes a light source that outputs light and a displaypanel that forms a virtual image using light output from the lightsource, and has the same function as a small projector. The light sourcemay be implemented with, for example, an LED, and the display panel maybe implemented with, for example, Liquid Crystal on Silicon (LCoS).

The eye-tracking sensor 3100 may be mounted at a position where thepupil of a user wearing an augmented reality device can be tracked, andmay transmit a signal corresponding to user's gaze to the processor3300. The eye-tracking sensor 3100 may detect gaze information such as agaze direction toward the user's eye, a pupil position of the user'seye, or coordinates of a center point of the pupil. The processor 3300may determine a shape of eye movement based on the user's gazeinformation detected by the eye-tracking sensor 3100. For example, theprocessor 3300, based on gaze information obtained from an eye-trackingsensor, may determine various types of eye movement, including fixationto look at any one place, pursuit to follow moving objects, a saccade inwhich the gaze moves quickly from one gaze point to another.

FIG. 30 is a block diagram of a schematic configuration of aneye-tracking sensor provided in the electronic device of FIG. 29 .

The eye-tracking sensor 3100 includes an illumination optical unit 3110,a detection optical unit 3120, a signal processor 3150, and a memory3160. The illumination optical unit 3110 may include a light source thatradiates light, for example, infrared light at a position of an object(user's eye). The detection optical unit 3120 detects reflected lightand may include a meta lens 3130 and a sensor 3140. The signal processor3150 calculates a pupil position of the user's eye from a result ofsensing by the detection optical unit 3120.

As the meta lens 3130, any one or a combination or modified example ofthe meta-optical devices according to the above-described embodimentsmay be used. The meta lens 3130 may condense light from the object tothe sensor 3140. An incident angle of light incident on the sensor 3140in the eye-tracking sensor 3100 located very close to the user's eyesmay be, for example, about 30 degrees or more. The meta lens 3130 has astructure including a compensation area, and efficiency degradation isreduced even for light having a larger incident angle. Therefore, theaccuracy of eye tracking may be improved.

The above-described meta-optical device may exhibit high diffractionefficiency because discontinuity of a phase profile is reduced.

The above-described meta-optical device may exhibit good diffractionefficiency even for incident light having a larger incident angle.

The above-described meta-optical device may be used as a lens, a beamdeflector, a beam shaper, and the like, and may be employed in variouselectronic devices utilizing these.

The foregoing exemplary embodiments are merely exemplary and are not tobe construed as limiting. The present teaching can be readily applied toother types of apparatuses. Also, the description of the exemplaryembodiments is intended to be illustrative, and not to limit the scopeof the claims, and many alternatives, modifications, and variations willbe apparent to those skilled in the art.

What is claimed is:
 1. A meta-optical device comprising: a plurality ofphase modulation areas arranged in a first direction and configured tomodulate a phase of an incident light, each of the plurality of phasemodulation areas comprising a plurality of nanostructures; and acompensation area located between a k^(th) phase modulation area and a(k+1)^(th) phase modulation area adjacent to each other, from among theplurality of phase modulation areas, and comprising a compensationstructure for buffering an effective refractive index change occurringin a boundary area between the k^(th) phase modulation area and the(k+1)^(th) phase modulation area according to respective rules of thek^(th) phase modulation area and the (k+1)^(th) phase modulation area,wherein N is a number of the plurality of phase modulation areas, k andN are natural numbers, and k is equal to or greater than 1 and less thanN, wherein the plurality of phase modulation areas have a circular shapeor an annular shape surrounding the circular shape, and the firstdirection is a radial direction that extends from a center of thecircular shape toward a boundary of the meta-optical device, and whereinsizes of the plurality of nanostructures in the k^(th) phase modulationarea change according to a first pattern in the radial direction, sizesof the plurality of nanostructures in the (k+1)^(th) phase modulationarea change according to a second pattern in the radial direction, and asize of the compensation structure located between the k^(th) phasemodulation area and the (k+1)^(th) phase modulation area does not followthe first pattern and the second pattern.
 2. The meta-optical device ofclaim 1, wherein the k^(th) phase modulation area and the (k+1)^(th)phase modulation area are configured to modulate the phase of theincident light to have a same sign of a phase change slope according toa position in the first direction.
 3. The meta-optical device of claim2, wherein, among the plurality of nanostructures in the k^(th) phasemodulation area, a width of a nanostructure closest to the compensationarea in the first direction is w_(a), among the plurality ofnanostructures in the (k+1)^(th) phase modulation area, a width of ananostructure closest to the compensation area in the first direction isw_(b), and a width w_(c) of the compensation structure is between w_(a)and w_(b).
 4. The meta-optical device of claim 3, wherein thecompensation structure comprises two or more compensation structureshaving a same width in the first direction and arranged in the firstdirection.
 5. The meta-optical device of claim 3, wherein thecompensation structure comprises two or more compensation structuresarranged in the first direction, and wherein widths of the two or morecompensation structures gradually change with a pattern of change fromw_(a) to w_(b) in the first direction.
 6. The meta-optical device ofclaim 1, wherein, when the plurality of phase modulation areas arem^(th) areas, and m is greater than or equal to 2 and increases from 2to N in an order from the center, all of the m^(th) areas have a phasemodulation range of a first phase to a second phase in the radialdirection, and the first phase and the second phase are different fromeach other and are between −2π and 2π.
 7. The meta-optical device ofclaim 6, wherein a difference between the first phase and the secondphase is a 2π or less.
 8. The meta-optical device of claim 1, whereinwidths of the plurality of phase modulation areas in the radialdirection decrease in a direction from the center to the boundary of themeta-optical device.
 9. The meta-optical device of claim 1, wherein thecompensation area comprises a plurality of compensation areas, andwidths of the plurality of compensation areas that are arranged in theradial direction have a same value or decrease in a direction from thecenter to the boundary of the meta-optical device.
 10. The meta-opticaldevice of claim 1, wherein the compensation area comprises a pluralityof compensation areas, and in a phase modulation area and a compensationarea at a position adjacent to each other, from among the plurality ofphase modulation areas and the plurality of compensation areas, a ratioof a width of the compensation area to a width of the phase modulationarea increases in a direction from the center to the boundary of themeta-optical device.
 11. The meta-optical device of claim 10, whereinthe ratio is 25% or less.
 12. The meta-optical device of claim 1,wherein, when a radius of the meta-optical device is R, a distance ofthe compensation area from the center is greater than R/2.
 13. Themeta-optical device of claim 1, wherein, when an incident angle of theincident light is θ, the compensation area is provided at a positionwhere θ is greater than or equal to 30°.
 14. The meta-optical device ofclaim 1, wherein each of the plurality of nanostructures and thecompensation structure has a pillar shape.
 15. The meta-optical deviceof claim 14, further comprising: a substrate configured to support theplurality of nanostructures and the compensation structure; and asurrounding material layer covering the plurality of nanostructures andthe compensation structure and having a refractive index different fromrefractive indices of the plurality of nanostructures and thecompensation structure.
 16. The meta-optical device of claim 1, whereinthe plurality of nanostructures and the compensation structure arearranged in a multilayer structure stacked in a second directionperpendicular to the first direction.
 17. The meta-optical device ofclaim 16, wherein the plurality of nanostructures comprise a pluralityof first nanostructures arranged on a first layer and a plurality ofsecond nanostructures arranged on a second layer, and the compensationstructure comprises a first compensation structure arranged on the firstlayer and a second compensation structure arranged on the second layer.18. The meta-optical device of claim 17, wherein, when viewed from thesecond direction, the first compensation structure and the secondcompensation structure are arranged to be offset with respect to eachother in the first direction.
 19. The meta-optical device of claim 18,wherein a length in the first direction in which the first compensationstructure and the second compensation structure are offset from eachother increases as a position of the compensation area becomes fartheraway from the center.
 20. The meta-optical device of claim 17, furthercomprising: a substrate configured to support the plurality of firstnanostructures and the first compensation structure; and a firstsurrounding material layer filling an area between the plurality offirst nanostructures and the first compensation structure on thesubstrate and having a refractive index different from refractiveindices of the plurality of first nanostructures and the firstcompensation structure.
 21. The meta-optical device of claim 20, furthercomprising: a second surrounding material layer filling an area betweenthe plurality of second nanostructures and the second compensationstructure on the first surrounding material layer and having arefractive index different from refractive indices of the plurality ofsecond nanostructures and the second compensation structure.
 22. Themeta-optical device of claim 20, further comprising a second surroundingmaterial layer arranged on the substrate, and each of the plurality ofsecond nanostructures and the second compensation structure has a holeshape such than the second surrounding material layer is engraved. 23.The meta-optical device of claim 1, wherein when a center wavelength ofthe incident light is λ₀, heights of the plurality of nanostructures andthe compensation structure are greater than λ₀/2 and less than 4λ₀. 24.The meta-optical device of claim 1, wherein the meta-optical device is alens.
 25. The meta-optical device of claim 1, wherein widths of theplurality of phase modulation areas in the first direction have an equalvalue.
 26. The meta-optical device of claim 1, wherein the meta-opticaldevice is a beam deflector.
 27. The meta-optical device of claim 1,wherein the meta-optical device is a beam shaper.
 28. The meta-opticaldevice of claim 1, wherein the incident light has an infrared wavelengthor a visible light wavelength.
 29. A meta-optical device comprising: aplurality of phase modulation areas arranged in a first direction andconfigured to modulate a phase of an incident light, each of theplurality of phase modulation areas comprising a plurality ofnanostructures, and a compensation area located between a k^(th) phasemodulation area and a (k+1)^(th) phase modulation area adjacent to eachother, from among the plurality of phase modulation areas, andcomprising a compensation structure for buffering an effectiverefractive index change occurring in a boundary area between the k^(th)phase modulation area and the (k+1)^(th) phase modulation area accordingto respective rules of the k^(th) phase modulation area and the(k+1)^(th) phase modulation area, wherein N is a number of the pluralityof phase modulation areas, k and N are natural numbers, and k is equalto or greater than 1 and less than N, the compensation area comprises aplurality of compensation areas, and a ratio of a number of theplurality of compensation areas to a number of the plurality of phasemodulation areas is 50% or more.
 30. A meta-optical device comprising: aplurality of phase modulation areas arranged in a first direction andconfigured to modulate a phase of an incident light, each of theplurality of phase modulation areas comprising a plurality ofnanostructures, and a compensation area located between a k^(th) phasemodulation area and a (k+1)^(th) phase modulation area adjacent to eachother, from among the plurality of phase modulation areas, andcomprising a compensation structure for buffering an effectiverefractive index change occurring in a boundary area between the k^(th)phase modulation area and the (k+1)^(th) phase modulation area accordingto respective rules of the k^(th) phase modulation area and the(k+1)^(th) phase modulation area, wherein N is a number of the pluralityof phase modulation areas, k and N are natural numbers, and k is equalto or greater than 1 and less than N, the meta-optical device furthercomprises a substrate and a surrounding material layer arranged on thesubstrate, and each of the plurality of nanostructures and thecompensation structure has a hole shape such that the surroundingmaterial layer is engraved.